Thin film magnetic head having thin film coil embedded in first insulating layer covered with second insulating layer

ABSTRACT

On a first magnetic layer  27,  is formed a ring-shaped insulating layer  28  whose air bearing surface side edge defines a reference position for a throat height, and after forming a write gap layer  29,  a second magnetic layer  30  is formed such that the second magnetic layer extends over the ring-shaped insulating layer  28.  The write gap layer is selectively removed by performing an etching process using the second magnetic layer as a mask, and then the first magnetic layer is partially removed over a part of its thickness to form a trim structure. After forming a thin film coil  33, 35  within the ring-shaped insulating layer, a third magnetic layer is formed to be brought into contact with a rear portion of the second magnetic layer  31.  The third magnetic layer may be contacted with a surface, a surface and side walls or a surface, side walls and an end surface of rear portion of the second magnetic layer. In the thin film magnetic head, a pole chip defining a track width is narrow, magnetic flux saturation and leakage of magnetic flux can be suppressed in spite of a short throat height, and a high recording efficiency can be attained. The invention provides a method of manufacturing easily the thin film magnetic head having such superior performance with a high yield.

This is a Continuation of application Ser. No. 09/592,918 filed Jun. 13,2000 now U.S. Pat. No. 6,609,291 which in turn is a Division ofapplication Ser. No. 09/099,461 filed Jun. 18, 1998 now U.S. Pat. No.6,130,805 issued Oct. 10, 2000. The entire disclosure of the priorapplications is hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thin film magnetic head and a methodof manufacturing the same, and more particularly to technique ofimproving a performance of an inductive type thin film writing magnetichead of a composite type thin film magnetic head constructed by stackingthe inductive type thin film writing magnetic head and amagnetoresistive type reading magnetic head one on the other.

2. Description of the Related Art

Recently a surface recording density of a hard disc device has beenimproved, and it has been required to develop a thin film magnetic headhaving an improved performance accordingly. In order to improve aperformance of a reading magnetic head, a reproducing head utilizing amagnetoresistive effect has been widely used. As the reproducingmagnetic head utilizing the magnetoresistive effect, an AMR reproducingelement utilizing a conventional anisotropic magnetoresistive (AMR)effect has been widely used. There has been further developed a GMRreproducing element utilizing a giant magnetoresistive (GMR) effecthaving a resistance change ratio higher than the normal anisotropicmagnetoresistive effect by several times. In the present specification,these AMR and GMR reproducing elements are termed as a magnetoresistivereproducing element or MR reproducing element.

By using the AMR reproducing element, a very high surface recordingdensity of several gigabits per a unit square inch has been realized,and a surface recording density can be further increased by using theGMR element. By increasing a surface recording density in this manner,it is possible to realize a hard disc device which has a very largestorage capacity of more than 10 gigabytes and is still small in size.

A height of a magnetoresistive reproducing element is one of factorswhich determine a performance of a reproducing head including amagnetoresistive reproducing element. This height is generally called MRHeight, here denoted by MRH. The MR height MRH is a distance measuredfrom an air bearing surface on which one edge of the magnetoresistivereproducing element is exposed to the other edge of the element remotefrom the air bearing surface. During a manufacturing process of themagnetic head, a desired MR height MRH can be obtained by controlling anamount of polishing the air bearing surface.

At the same time, a performance of a recording head has been alsorequired to be improved. In order to increase a surface recordingdensity, it is necessary to make a track density on a magnetic recordmedium as high as possible. For this purpose, a width of a pole portionat the air bearing surface has to be reduced to a value within a rangefrom several micron meters to several sub-micron meters. In order tosatisfy such a requirement, the semiconductor manufacturing process hasbeen adopted for manufacturing the thin film magnetic head. One offactors determining a performance of an inductive type thin film writingmagnetic film is a throat height TH. This throat height TH is a distanceof a pole portion measured from the air bearing surface to an edge of aninsulating layer which serves to separate electrically a thin film coilfrom the air bearing surface. It has been required to shorten thisdistance as small as possible. Also this throat height TH is determinedby an amount of polishing the air bearing surface.

FIGS. 1 a, 1 b–9 a are cross sectional views showing successive steps ofa known method of manufacturing a conventional typical thin filmmagnetic head, said cross sectional views being cut along a planeperpendicular to the air bearing surface and cut along a plane parallelwith the air bearing surface. FIGS. 10–12 are a cross sectional viewillustrating a completed thin film magnetic head cut along a planeperpendicular to the air bearing surface, a cross sectional view of thepole portion cut along a plane parallel with the air bearing surface,and a plan view depicting the pole portion. This magnetic head belongsto a composite type thin film magnetic head which is constructed bystacking an inductive type thin film writing magnetic head and amagnetoresistive type thin film reading magnetic head one on the other.

At first, as illustrated in FIGS. 1 a and 1 b, on a substrate 1 made ofa hard non-magnetic material such as aluminum-titan-carbon (AlTiC), isdeposited an insulating layer 2 made of alumina (Al₂O₃) and having athickness of about 5–10 μm. Then, as depicted in FIGS. 2 a and 2 b, abottom shield layer 3 constituting a magnetic shield for the MRreproducing magnetic head is formed to have a thickness of about 3 μm onthe insulating layer.

Then, after depositing by sputtering a shield gap layer 4 made of analumina with a thickness of 100–150 nm as shown in FIGS. 3 a and 3 b, amagnetoresistive layer 5 having a thickness of several tens nano metersand being made of a material having the magnetoresistive effect, and themagnetoresistive layer is shaped into a desired pattern by a highlyprecise mask alignment.

Next, as represented in FIGS. 4 a and 4 b, a shield gap layer 6 isformed such that the electromagnetic layer 5 is embedded within theshield gap layers 4, 6.

Then a magnetic layer 7 made of a permalloy and having a thickness of 3μm is formed as shown in FIGS. 5 a and 5 b. This magnetic layer 7 servesnot only as an upper shield layer for magnetically shielding the MRreproducing element together with the above mentioned bottom shieldlayer 3, but also as a bottom magnetic layer of the inductive typewriting thin film magnetic head to be manufactured later. Here, for thesake of explanation, the magnetic layer 7 is called a first magneticlayer, because this magnetic layer constitutes one of magnetic layersforming the thin film writing magnetic head.

Next, after forming, on the first magnetic layer 7, a write gap layer 8made of a nonmagnetic material such as alumina to have a thickness ofabout 200 nm, a second magnetic layer 8 made of a magnetic materialhaving a high saturated magnetic flux density such as a permalloy (Ni:50 wt %, Fe: 50 wt %) and iron nitride (FeN) and the second magneticlayer is shaped into a desired pattern by means of a precise maskalignment.

This second magnetic layer 24 having a desired pattern is called a polechip and a track width is determined by a width of the pole chip.

During this process, a dummy pattern 9′ for connecting the bottom pole(first magnetic layer) to an upper pole (third magnetic layer) to beformed later is formed. Then a through hole can be easily formed aftermechanical polishing or chemical-mechanical polishing (CMP).

In order to prevent an increase of an effective track width, that is, inorder to prevent a spread of a magnetic flux at the lower pole during awriting operation, the gap layer 8 and bottom pole (first magneticlayer) near the pole chip 9 are removed by an ion beam etching such asan ion milling. This condition is illustrated in FIG. 5, and thisstructure is called a trim structure. It should be noted that thisportion constitutes the pole portion of the first magnetic layer.

Next, as illustrated in FIGS. 6 a and 6 b, an insulating layer 10 suchas an alumina layer is formed to have a thickness of about 3 μm, andthen an assembly is flattened by, for instance CMP.

After that, an electrically insulating photo-resist layer 11 is formedin accordance with a given pattern by a highly precise mask alignment,and then a first layer of a thin film coil 12 made of, for instancecopper is formed on the photo-resist layer 11.

Next, as depicted in FIGS. 7 a and 7 b, an insulating photo-resist layer13 is formed on the thin film coil 12 by a highly precise maskalignment, a surface is flattened by baking at a temperature of, forinstance 250–300° C.

Furthermore, as shown in FIGS. 8 a and 8 b, on the thus flattenedsurface of the photo-resist layer 13, a second layer thin film coil 14is formed. Then, a photo-resist layer 15 is formed on the second layerthin film coil 14 by a highly precise mask alignment, and a bakingprocess is carried again at a temperature of, for instance 250° C.

A reason for forming the photo-resist layers 11, 13 and 15 by a highlyprecise mask alignment is that the throat height TH and MR height aredetermined with respect to edges of these photo-resist layers on a sideof the pole portion.

Next, as shown in FIGS. 9 a and 9 b, a third magnetic layer 16 made of,for instance a permalloy is formed on the second magnetic layer (polechip) 9 and photo-resist layers 11, 13 and 15 such that the thirdmagnetic layer has a thickness of 3 μm and is shaped into a desiredpattern.

The third magnetic layer 16 is brought into contact with the firstmagnetic layer 7 at a position remote from the pole portion by means ofthe dummy pattern 9′, and therefore the thin film coil 12, 14 passthrough a closed magnetic yoke structure constituted by the first,second and third magnetic layers.

Furthermore, an overcoat layer 25 made of an alumina is deposited on anexposed surface of the third magnetic layer 16.

Finally, a side wall at which the magnetoresistive layer 5 and gap layer8 are formed is polished to form an air bearing surface (ABS) 18. Duringthe formation of the air bearing surface 18, the magnetoresistive layer5 is also polished to obtain an MR reproducing element 19. In thismanner, the above mentioned throat height TH and MR height MRH aredetermined by the polishing. This condition is shown in FIG. 10. In anactual manufacturing process, contact pads for establishing electricalconnections to the thin film coils 12, 14 and MR reproducing element 19are formed, but these contact pads are not shown in the drawings.

As shown in FIG. 10, an angle θ between a straight line S connectingside edges of the photo-resist layers 11, 13 and 15 isolating the thinfilm coils 12, 14 and an upper surface of the third magnetic layer 16 iscalled an apex angle. This apex angle is one of important factors fordetermining a property of the thin film magnetic head together with thethroat height TH and MR height MRH.

Furthermore, as shown in the plan view of FIG. 12, a width W of the poleportion 20 of the second magnetic layer 9 and third magnetic layer 16 issmall. A width of tracks recorded on a record medium is determined bysaid width W, and therefore it is necessary to make this width W assmall as possible in order to realize a high surface recording density.It should be noted that in the drawing, the thin film coils 12, 14 aredenoted to be concentric for the sake of simplicity.

In the known method of manufacturing the thin film magnetic head, thereis a special problem in the formation of the upper pole (yoke pole)after the formation of the thin film coil in a precise manner along theoutwardly protruded coil portion, particularly along an inclined portion(apex) thereof, said coil portion being covered with the photo-resistinsulating layers. That is to say, in the known method, upon forming theupper pole, after an upper pole material such as permalloy is depositedby plating on the outwardly protruded coil portion having a height ofabout 7–10 μm, a photo-resist is applied to have a thickness of 3–4 μm,and then the layer is shaped into a given pattern by utilizing thephotolithography. Since a thickness of the photo-resist layer providedon the upper portion of the coil portion should be at least 3 μm, thephoto-resist layer has to be applied such that a portion of thephoto-resist at a bottom of the outwardly protruded coil portion wouldhave a thickness of 8–10 μm.

On the other hand, in order to form a narrow track of the recording headnear the edges of the photo-resist insulating layers (for instance,layers 11 and 13 in FIG. 7), the upper pole formed on the write gaplayer provided on the surface of the outwardly protruded coil portion aswell as on the flat surface should be patterned to have a width of about1 μm, said coil portion and flat portion having a level difference ofabout 10 μm. Therefore, it is necessary to form the photo-resist layerhaving a thickness of 8–10 μm and a pattern having a width of 1 μm.

However, when a narrow pattern having a width of 1 μm is to be formedwith the thick photo-resist layer having a thickness of 8–10 μm, a toppole which can realize a narrow track could hardly be manufacturedaccurately due to a deformation of a pattern by light reflection duringa light exposure in a photolithography and an inevitable decrease in aresolution caused by a large thickness of the photo-resist layer.

Under the above circumstances, as shown in the above explained knownmethod, the above problem has been solved by writing data with the aidof the pole chip which can realize a narrow track width and afterforming the pole chip, the upper pole is connected to the pole chip.That is to say, the division structure is adopted, in which the upperyoke is divided into the pole chip defining the track width and theupper pole for introducing a magnetic flux into the pole chip.

However, the thin film magnetic head, particularly the recordingmagnetic head formed in the above mentioned manner still has thefollowing problems.

-   (1) The throat height TH and MR height MRH are determined, while the    edge of the insulating layer isolating the thin film coil on a side    of the pole portion is used as a positional reference, and the    insulating layer is generally made of an organic insulating    photo-resist layer and thus is liable to be affected by heat.    Therefore, the insulating film is liable to be melt or softened by    the heating treatment at about 250° C. during the formation of the    thin film coil, and a pattern of the insulating layer might be    deformed. Moreover, a reference position of zero throat height is    determined by an end of the pole chip 9 opposite to the air bearing    surface 18, and the edge of the pole chip pattern is rounded off due    to a fact that the pole chip has a narrow width W, and therefore a    position of the end of the pole chip might be shifted. In this    manner, in the composite type thin film magnetic head, it is    difficult to determine the reference position of throat height zero    accurately, and thus the thin film magnetic head having desired    throat height TH and MR height MRH according to the desired design    values could not be manufacture with a high yield.-   (2) The surface of the pole chip 9 is coupled with the surface of    the third magnetic layer 16. In order to make the width W of the    pole chip narrow as explained above and in order to attain a good    magnetic property, a length of the pole chip has to be short such as    about 1 μm. Therefore, a contact area of the pole chip and third    magnetic layer is small. Moreover, the third magnetic layer is    brought into contact with the pole chip perpendicularly, and thus a    magnetic flux is liable to be saturated at this portion, a writing    property, particularly a magnetic flux rise time is degraded.-   (3) If there is an alignment error in the photolithography for    forming the third magnetic layer 16 on the pole chip 9 having the    narrow width W, a center of the pole chip 9 and a center of the pole    portion 20 of the third magnetic layer 16 viewed from the air    bearing surface might be shifted relative to each other. If the    center of the pole chip 9 is deviated from the center of the pole    portion 20 of the third magnetic layer 16, there might be produced a    large leakage of the magnetic flux from the pole portion of the    third magnetic layer and data might be written by this leaked    magnetic flux. Therefore, an effective track width is increased and    data might be recorded in a region other than a desired region into    which the data has to be recorded.

SUMMARY OF THE INVENTION

The present invention has for its object to provide a thin film magnetichead, in which the above mentioned problems can be solved and theinsulating layer constituting a positional reference for the air bearingsurface is not melt or softened by a heating treatment for forming thethin film coil at a temperature of about 250° C., and thus the throatheight TH and MR height MRH accurately corresponding to desired designvalues can be obtained stably.

It is another object of the invention to provide a thin film magnetichead, in which a surface area at a contact with the pole chip and theupper pole can be effectively increased, and therefore undesiredsaturation of the magnetic flux at the pole portion can be prevented.

It is another object of the invention to provide a thin film magnetichead, in which undesired increases in an effective track width and in amanufacturing yield can be mitigated.

It is another object of the invention to provide a thin film magnetichead, in which a track width can be reduced by decreasing a height ofthe thin film coil, and the number of coil windings can be effectivelyincreased.

It is another object of the invention to provide a method ofmanufacturing the thin film magnetic head having the above mentionedsuperior characteristics in an accurate manner with a high yield.

According to the invention, a thin film magnetic head comprises:

a first magnetic layer having a pole portion;

a second magnetic layer having a pole portion whose end surfaceconstitutes an air bearing surface together with said pole portion ofthe first magnetic layer, said pole portion of the second magnetic layerhaving a width defining a width of a record track on a magnetic recordmedium to be opposed to the air bearing surface;

a third magnetic layer which is brought into contact with said secondmagnetic layer on a side opposite to said first magnetic layer and ismagnetically coupled with said first magnetic layer at a rear positionremote from the air bearing surface;

a gap layer made of a non-magnetic material and being interposed atleast between said pole portion of the first magnetic layer and saidpole portion of the second magnetic layer;

a thin film coil having a portion which is supported by an insulatingmaterial in an electrically isolated manner between said first magneticlayer and said second and third magnetic layers; and

a substrate supporting said first, second and third magnetic layers, gaplayer and thin film coil;

wherein a band-shaped or strip-shaped insulating layer having at least aportion whose edge on a side of the pole portion defines a referenceposition for the air bearing surface is provided on said first magneticlayer, at least a surface of said insulating layer opposing to saidfirst magnetic layer is covered with the non-magnetic materialconstituting said gap layer, and said thin film coil is provided in arear region with respect to said insulating layer.

In the thin film magnetic head according to the invention, the thirdmagnetic layer may be coupled with said second magnetic layer only atthe surface of the second magnetic layer or at the surface and sidewalls of the second magnetic layer or at the surface, side walls and endsurface of the second magnetic layer.

According to the invention, said insulating layer may have various planconfiguration, but it is most preferable to form the ring-shapedinsulating layer and the thin film coil is arranged in an inner area ofthe ring. Furthermore, the band-shaped insulating layer may bepreferably made of an inorganic insulating material such as alumina,silicon oxide and silicon nitride.

In a preferable embodiment of the thin film magnetic head according tothe invention, said second magnetic layer is formed such that it extendsnot only over the pole portion of the first magnetic layer, but alsoover the band-shaped insulating layer situating behind the pole portion.In this case, it is preferable to gradually increase a width of thesecond magnetic layer on the band-shaped insulating layer. A wideningangle of the rear portion of the second magnetic layer is preferablymade identical with that of the third magnetic layer, said angle being30–180°.

In the thin film magnetic head according to the invention, it ispreferable to make said second magnetic layer of a magnetic materialhaving a high saturation flux density such as permalloy (Ni: 50 Wt %, Fe50 Wt %), iron nitride (FeN), Fe—Cr—Zr based amorphous alloy and Fe—Cbased amorphous alloy.

In a preferable embodiment of the thin film magnetic head according tothe invention, a front end of said third magnetic layer is retarded fromthe air bearing surface such that a contact portion between the secondmagnetic layer and the third magnetic layer is not exposed on the airbearing surface. In this case, it is preferable to make a retardingdistance of the front end of the third magnetic layer substantiallyequal to the throat height TH.

Furthermore, in another preferable embodiment of the thin film magnetichead according to the invention, the thin film magnetic head isconstructed as a composite type thin film magnetic head by providing areading magnetoresistive element in an electrically insulated andmagnetically shielded manner such that an edge of the magnetoresistiveelement is exposed on said air bearing surface.

According to the invention, a method of manufacturing a thin filmmagnetic head comprises the steps of:

forming a first magnetic layer having a pole portion such that the firstmagnetic layer is supported by a substrate;

forming a band-shaped insulating layer on said first magnetic layer,said insulating layer having at least a portion whose edge defines areference position for an air bearing surface;

forming a gap layer made of a non-magnetic material on at least saidpole portion of the first magnetic layer and on said insulating layer;

forming a second magnetic layer on said gap layer at least at a portionwhich situates on said first magnetic layer;

forming a thin film coil in a rear region on a side of the band-shapedinsulating layer opposite to said air bearing surface such that the thinfilm coil is supported by an insulating material in an electricallyisolated manner;

forming a third magnetic layer such that the third magnetic layer iscoupled with said second magnetic layer as well as with said firstmagnetic layer at a rear portion opposite to said air bearing surface;and

polishing the substrate, pole portions of the first and second magneticlayers and gap layer sandwiched by these magnetic layers to form the airbearing surface which is to be opposed to a magnetic record medium.

In the method of manufacturing the thin film magnetic head according tothe invention, the third magnetic layer may be coupled with the surfaceof the second magnetic layer or with the surface and side walls of thesecond magnetic layer or with the surface, side walls and end surface ofthe second magnetic layer.

In the method of manufacturing the thin film magnetic head according tothe invention, it is preferable to form said second magnetic layer suchthat not only the pole portion of the first magnetic layer, but also theinsulating layer behind the pole portion are covered with the secondmagnetic layer. In this case, it is preferable to increase gradually awidth of the rear portion of the second magnetic layer.

In a preferable embodiment of the method of manufacturing the thin filmmagnetic head according to the invention, said band-shaped insulatinglayer is formed as a ring-shape, and prior to the formation of the thinfilm coil, a surface of the second magnetic layer, a surface of thering-shaped insulating layer and an inner area surrounded by thering-shaped insulating layer are covered with a non-magnetic andnon-conductive film. In this case, it is particularly preferable topolish the surface of the rear portion of the second magnetic layer anda surface of the non-magnetic and non-conductive film such that thesesurfaces become co-planer. By proving such a flat surface, the thin filmcoil can be formed much more accurately.

In the method of manufacturing the thin film magnetic head according tothe invention, it is preferable to form said third magnetic layer suchthat a front end of the third magnetic layer is retarded from the airbearing surface and a contact portion of the second and third magneticlayers is not exposed on the air bearing surface.

Moreover, in the method of manufacturing the thin film magnetic headaccording to the invention, it is also possible to constitute acomposite type thin film magnetic head by forming a magnetoresistivereproducing element between said substrate and said first magnetic layersuch that the element is magnetically shielded and electricallyisolated. In this case, a first shield layer is formed on the substrate,the magnetoresistive material layer embedded within a shield gap layeris formed on the first shield layer, and said first magnetic layer alsoserving as a second shield layer is formed. During a polishing step forforming the air bearing surface, said magnetoresistive material layer aswell as the first shield layer and shield gap layer are polished to formthe magnetoresistive reproducing element having an edge exposed on theair bearing surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a, 1 b–9 a, 9 b are cross sectional views cut along a planeperpendicular to the air bearing surface as well as a plane parallelwith the air bearing surface and showing successive steps ofmanufacturing a known composite type thin film magnetic head;

FIG. 10 is a cross sectional view of the completed known thin filmmagnetic head cut along a plane perpendicular to the air bearingsurface;

FIG. 11 a cross sectional view showing the pole portion of the completedknown thin film magnetic head cut along a plane perpendicular to the airbearing surface;

FIG. 12 is a plan view illustrating the completed known thin filmmagnetic head;

FIGS. 13 a, 13 b–18 a, 18 b are cross sectional views cut along a planeperpendicular to the air bearing surface as well as along a planeparallel with the air bearing surface showing successive steps of anembodiment of the thin film magnetic head manufacturing method accordingto the invention;

FIG. 19 is a plan view illustrating a second magnetic layer shown inFIG. 18;

FIG. 20 is a plan view depicting another embodiments of the secondmagnetic layer;

FIGS. 21 a, 21 b–25 a, 25 b are cross sectional views cut along a planeperpendicular to the air bearing surface as well as along a planeparallel with the air bearing surface showing succeeding steps;

FIG. 26 is a plan view illustrating a shape of the third magnetic layersuitable for the second magnetic layer;

FIGS. 27 a and 27 b are cross sectional views cut along a planeperpendicular to the air bearing surface as well as a plane parallelwith the air bearing surface showing a completed thin film magnetic headaccording to the invention;

FIG. 28 is a plan view illustrating the completed thin film magnetichead according to the invention;

FIGS. 29 a and 29 b are cross sectional views cut along a planeperpendicular to the air bearing surface as well as along a planeparallel with the air bearing surface showing another embodiment of thethin film magnetic head according to the invention;

FIGS. 30 a–30 i are plan views showing several embodiments of theband-shaped insulating layer provided in the thin film magnetic headaccording to the invention;

FIGS. 31 a, 31 b–34 a, 34 b are cross sectional views cut along a planeperpendicular to the air bearing surface as well as along a planeparallel with the air bearing surface illustrating successive steps of asecond embodiment of the method of manufacturing the composite type thinfilm magnetic head according to the invention;

FIG. 35 is a plan view depicting a condition shown in FIG. 34;

FIGS. 36 a, 36 b and 37 a, 37 b are cross sectional views cut alongplanes perpendicular to and parallel with the air bearing surfaceshowing succeeding steps;

FIG. 38 is a perspective view illustrating a condition shown in FIG. 37;

FIGS. 39 a, 39 b and 40 a, 40 b are cross sectional views cut alongplanes perpendicular to and parallel with the air bearing surfaceshowing succeeding steps;

FIG. 41 is a perspective view illustrating a condition shown in FIG. 40;

FIGS. 42 a and 42 b are cross sectional views cut along planesperpendicular to and parallel with the air bearing surface showing acompleted thin film magnetic head;

FIG. 43 is a plan view depicting a shape of the band-shaped insulatinglayer in another embodiment of the thin film magnetic head according tothe invention;

FIG. 44 is a plan view showing the band-shaped insulating layer inanother embodiment of the thin film magnetic head according to theinvention; and

FIG. 45 is a diagrammatic plan view illustrating a configuration of acoupled portion of the second magnetic layer in another embodiment ofthe thin film magnetic head according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 13–26 show successive steps of an embodiment of the method ofmanufacturing the thin film magnetic head according to the invention,and FIGS. 27 and 28 are longitudinal cross sectional view and plan view,respectively showing a completed thin film magnetic head according tothe invention. In the drawings showing the steps, (a) represents a crosssectional view cut along a plane perpendicular to an air bearing surfaceand (b) illustrates a cross sectional view cut along a plane parallelwith the air bearing surface. The thin film magnetic head of the presentembodiment is constructed as a composite type thin film magnetic headhaving an inductive type writing magnetic head and a MR reproducingelement stacked one on the other.

At first, as shown in FIGS. 13 a and 13 b, on a substrate 21 made of anAlTiC, is deposited an insulating layer 42 made of an alumina having athickness of about 3–5 μm.

Next, as shown in FIGS. 14 a and 14 b, on the alumina insulating layer22, a permalloy layer constituting a lower magnetic shield layer 23 isdeposited to have a thickness of about 3 μm by using a photo-resist filmas a mask by means of sputtering.

Next, an insulating layer 24′ made of an alumina is formed to a surfaceof this insulating layer is flattened by, for instance CMP. Then, ashield gap layer 24 made of an alumina is deposited by sputtering tohave a thickness of 100–200 nm as illustrated in FIGS. 16 a and 16 b,and then a magnetoresistive layer 25 forming the MR reproducing elementis formed to have a thickness of several tens nano meters and themagnetoresistive layer is patterned into a desired shape by means of ahighly precise mask alignment. After that a shield gap film 26 is formedsuch that the magnetoresistive layer 25 is embedded within the shieldgap layers 24, 26. Then, a first magnetic layer 27 having a thickness ofabout 3–4 μm is selectively formed.

After that, in order to remove any step, an alumina layer having athickness of 5–6 μm is formed on a whole surface, and then this aluminalayer is processed by CMP to expose the surface of the first magneticlayer 27.

Next, a band-shaped insulating layer 28 is formed by means of aphoto-resist to have a thickness of 2–5 μm and a width of 3–7 μm, saidinsulating layer including at least a portion whose edge opposing to thepole portion defines a reference position with respect to the throatheight TH and apex angle. In the present embodiment, said band-shapedinsulating layer is formed as a ring-shaped insulating layer, butaccording to the invention, it is always necessary to form thering-shaped insulating layer. That is to say, it is sufficient for theband-shaped insulating layer 28 to have the portion which defines thereference position with respect to the throat height TH, and thus aninner portion of the ring-shaped insulating layer is not necessary.However, when the ring-shaped insulating layer 28 having the innerportion is formed, the thin film coil can be manufactured accurately ina later step.

Next, as shown in FIGS. 18 a and 18 b, a write gap layer 29 made of analumina and having a thickness of 100–300 nm is formed at least on thepole portion of the first magnetic layer 36 and ring-shaped insulatinglayer 28. In this case, it is preferable to cover an inner area of theband-shaped insulating layer 28 with a non-magnetic layer constitutingthe write gap layer 29, because an insulation from the first magneticlayer can be maintained. When the surface of the band-shaped insulatinglayer 28 is covered with the alumina insulating layer 29, the followingmerit can be obtained.

The throat height TH is defined as a distance between the air bearingsurface and the edge of the ring-shaped insulating layer 28 on a side ofthe pole portion, but in actual manufacturing, since the edge of theinsulating layer could not been seen, it is assumed that said edge isformed at a desired position and the air bearing surface is polishedsuch that a desired throat height TH can be obtained by using this edgeposition as the reference position.

On the other hand, during a later step of forming the thin film coil, aheating treatment is carried out at about 250° C., and during thisheating treatment, the photo-resist layer constituting the-ring-shapedinsulating layer 28 is melt and a pattern size of the insulating layeris shifted. Therefore, a position of the above mentioned edge of thephoto-resist insulating layer 28 is also shifted, and thus a size of thethroat height TH formed by taking the edge position as the referenceposition might be deviated from a desired design value.

The MR height MRH which is defined as a height of the magnetoresistivereproducing element measured from the air bearing surface is alsodetermined by an amount of polishing the air bearing surface like as thethroat height TH. This polishing is performed while the edge of thering-shaped insulating layer 28 opposing to the pole portion is utilizedas the reference position, and thus if a position of this edge of theinsulating layer is shifted during the heating treatment, the MR heightis also deviated from the desired design value.

Moreover, if the photo-resist layers 33, 36 constituting the ring-shapedinsulating layer 28 and the insulating layer which isolates the thinfilm coil to be explained later are melt, the apex angle θ defined by aninclination angle of the side surface of these insulating layers mightbe also deviated. The performance of the thin film magnetic head alsodepends on this apex angle θ, and might be sometimes affected by thedeviation of the apex angle.

Therefore, it is important that a position of the edge of photo-resistlayer forming the ring-shaped insulating layer is not varied even underthe heating treatment of about 250° C. carried out the formation of thethin film coil. In the present embodiment, after forming the ring-shapedphoto-resist insulating layer 28, the alumina insulating layer 29constituting the write gap is formed such that the photo-resistinsulating layer is covered with the alumina insulating layer as shownin FIGS. 17 a and 17 b, and therefore the edge of the photo-resistinsulating layer 28 is no more shifted by the heating treatment andundesired deviations of the throat height TH as well as the MR heightMRH and apex angle θ from the desired design values can be effectivelysuppressed.

Next, as illustrated in FIGS. 18 a and 18 b, a second magnetic layer 30(pole chip) defining the track width W is selectively formed to have athickness of about 1—4 μm. Then, the write gap in the vicinity of thepole chip is selectively removed an opening, and the first magneticlayer 27 exposed in the opening is etched by, for instance an ion beammilling, to form the pole portion.

It should be noted that in the present invention, as shown by H in FIG.18 a, the pole portion means a portion of a region extending from theouter edge of the ring-shaped insulating layer 28 to an end surface ofthe stacked body, along said portion the first magnetic layer 27, writegap layer 29 and second magnetic layer 30 being adjoined with the widthW (see FIG. 18 b). Therefore, in a final product, after polishing theend surface to form the air bearing surface, the pole portion becomes aregion extending from the outer edge of the ring-shaped insulating layer28 to the air bearing surface and is identical with the throat heightTH.

According to the invention, upon forming the pole chip, it is importantthat the second magnetic layer 30 is extended not only over the poleportion but also over the surface of the ring-shaped insulating layer 28which is positioned behind the pole portion as depicted in FIG. 19. Inthe known thin film magnetic head in which the top pole is deposited onthe pole chip, a contact area between the pole chip and the top pole issmall and an end surface of the top pole is perpendicular to the surfaceof the pole chip. Therefore, a magnetic flux is liable to be saturatedat this portion and a sufficiently satisfactory writing property couldnot be obtained. According to the present invention, a contact areabetween the pole chip and the top pole is not limited to the poleportion, but is extended up to a rear portion such that the abovementioned saturation of magnetic flux can be effectively removed and asufficiently satisfactory writing property can be attained. In thiscase, if a sufficiently large contact area can be obtained, the contactregion between the pole chip and the top pole may be restricted to arear region with respect to the pole portion. In this specification, theterm “rear” means a direction remote from the air bearing surface.

According to the invention, a shape of the rear portion of the pole chipbehind the pole portion may be modified in various ways. For instance,the rear portion of the pole chip may be extended in a straight forwardmanner as shown in FIG. 19, or may be gradually widened as depicted inFIG. 20. At any rate, according to the invention, it is sufficient thatthe pole chip and top pole are contacted with each other in the rearregion behind the pole portion.

It should be noted that a length h of the backwardly extended portion ofpole chip behind the pole portion may be preferably set to about 2–5 μmwhich does not exceed a thickness of the ring-shaped insulating layer28, and more particularly to a value substantially equal to a thicknessof the top pole.

Furthermore, in the embodiment shown in FIG. 20, the rear portion of thepole chip behind the pole portion is widened at an angle of about 90°,but according to the invention, this widening angle is not limited onlyto such an angle, but may be set to an angle not larger than 180°, and amore preferably widening angle range is 45–180°.

In this manner, when the rear portion of the pole chip is widened like afan as shown in FIG. 20, not only the above mentioned saturation ofmagnetic flux does not occur, but also a more accurate pattern controlin the photolithography can be performed and the throat height TH can bemuch more accurately controlled.

After forming the second magnetic layer 30 as explained above, a firstlayer thin film coil is to be formed in a region surrounded by thering-shaped insulating layer 28. Prior to the formation of the thin filmcoil, a non-magnetic and non-conductive layer such as an alumina layerhaving a thickness of about 0.5–1.5 μm is deposited as illustrated inFIGS. 21 a and 21 b. By covering at least the area on which the thinfilm coil is to be formed with the non-magnetic and non-conductive layer31, an isolation between the first magnetic layer 27 and the thin filmcoil can be improved and a leakage of magnetic field can be effectivelyavoided. Moreover, it is preferable to cover not only the inside of thering-shaped insulating layer 28, but also the whole surfaces of thering-shaped insulating layer and second magnetic layer (pole chip) 30.

Next, as shown in FIGS. 22 a and 22 b, after forming a first layer thinfilm coil 32 made of a copper on the region surrounded by thering-shaped insulating layer 28, an insulating photo-resist layer 33 isformed with a highly precise mask alignment, and then a heatingtreatment is conducted at a temperature of, for instance 250° C. inorder to obtain a flat surface. In this manner, according to theinvention, the first layer thin film coil 32 is formed on the regionsurrounded by the ring-shaped insulating layer 28, and therefore a wholeheight of the thin film coil can be decreased. That is to say, in theknown thin film magnetic head, since the thin film is formed on theinsulating layer, when two or three layer thin film coil is formed inorder to improve a performance of the writing magnetic head, a height ofthe coil portion is increased. Then, it is difficult to reduce a trackwidth. According to the invention, at least the first layer thin filmcoil is formed within the ring-shaped insulating layer 28, an apexheight can be deceased accordingly. On the other hand, if the apexheight is made substantially identical with that of the known magnetichead, the number of coil turns may be increased accordingly and asuperior performance may be attained.

Next, as shown in FIGS. 23 a and 23 b, on a whole surface is formed analumina insulating layer 34 having a thickness of 4–5 μm, and then thesurface is flattened by, for instance CMP such that the first layer thinfilm coil 32 is covered with the insulating layer 34, but the pole chip(second magnetic layer), contact portions of the first layer thin filmcoil and a through hole (not shown) for connecting the bottom pole andtop pole (third magnetic layer) are exposed.

After that, as illustrated in FIGS. 24 a and 24 b, after forming asecond layer thin film coil 35, a photo-resist layer 36 is formed on thesecond layer thin film coil. Then, in order to flatten the surface, aheating treatment is conducted at a temperature of, for instance 250° C.

Next, a third magnetic layer (top pole) 37 made of, for instancepermalloy and having a thickness of 3 μm is selectively formed on thesecond magnetic layer (pole chi) 30 and photo-resist layer 36 inaccordance with a given pattern as shown in FIGS. 25 a and 25 b.

Upon forming the third magnetic layer 37, it is preferable that a frontend of the third magnetic layer is retarded from the air bearing surfaceby a distance equal to the throat height TH as shown in FIG. 25 a (inthe drawing, shown by L). This is due to a fact that when the front endof the third magnetic layer extends up to the air bearing surface, if apositional relationship between the pole chip and the tope pole isshifted largely on one side, a data writing might be carried out alsothrough the front end of the top pole and an effective track width mightbe widened, but when the front end of the third magnetic layer isretarded from the air bearing surface, such a demerit can be avoided.

It should be noted that if the front end of the top pole is retardedfrom the air bearing surface in the known thin film magnetic head, acontact area between the pole chip and the top pole is decreasedaccordingly and a leakage of magnetic flux could not be avoided.According to the present invention, since this contact area can besufficiently large by providing the rear portion behind the poleportion, even if the front end of the top pole is retarded from the airbearing surface, undesired leakage of magnetic flux does not occur.

Upon forming the third magnetic layer 37, it is desired that the thirdmagnetic layer follows a configuration of the second magnetic layer 30as shown in FIG. 20. Moreover, when the widening angle of the secondmagnetic layer 30 is small such as 30–60° as illustrated in FIG. 26, afront end portion of the third magnetic layer 37 may be formed to followthe shape of the second magnetic layer such that the third magneticlayer is also gradually widened at the widening angle of 30–60°, and arear portion of the third magnetic layer may be further widened at adesired widening angle.

In this manner, by forming the third magnetic layer such that it isgradually widened to cover the second magnetic layer 30, even if anerror occurs in an alignment between the pole chip 30 and the top pole37, a variation in a contact area therebetween is remained small and aleakage of magnetic flux can be avoided.

It should be noted that the third magnetic layer 37 is brought intocontact with the first magnetic layer 27 by means of the through holeprovided at a position remote from the pole portion, and the thin filmcoil 32, 35 passes through a closed magnetic path constituted by thefirst, second and third magnetic layers.

Next, as depicted in FIGS. 27 a and 27 b, an overcoat layer 38 made analumina and the like is deposited on an exposed surface of the thirdmagnetic layer 37.

Finally, as illustrated in FIGS. 27 and 28, a side wall on which themagnetoresistive layer 25 and gap layer 29 is polished to form an airbearing surface 39, which is to be opposed to a magnetic record medium.

During the polishing, the edge of ring-shaped insulating layer 28 on aside of the pole portion is utilized as the reference position for theair bearing surface 39, and therefore the throat height TH, MR heightMRH and apex angle θ can be accurately determined in accordance withdesired design values.

FIGS. 29 a and 29 b are cross sectional views showing another embodimentof the thin film magnetic head according to the invention, in which thepole chip 30 is formed to have a large thickness. By increasing athickness of the pole chip 30, a distance over which the front end ofthe top pole 37 is retarded from the air bearing surface 39 can beincreased. As a result of this, even if the front end of the top pole 37is closer to the air bearing surface due to a variation in process forthe air bearing surface, a writing operation to another track can beprevented and thus an undesired increase in an effective track width canbe much more effectively prevented.

In the embodiments so far explained, the band-shaped insulating layer 28having at least the portion whose edge on a side of the pole portionserves as the reference position for the air bearing surface is formedas the elliptical ring-shape as shown in FIG. 30 a. According to theinvention, the band-shaped insulating layer is not limited to such aring-shaped one, but may be formed in various shapes. For instance,substantially ring-shapes shown in FIGS. 30 b and 30 c, or parts ofelliptical, octagonal and rectangular ring-shapes as illustrated inFIGS. 30 d, 30 e and 30 f, respectively, or rectilinear shapes asdepicted in FIGS. 30 g, 30 h and 30 i.

Now a second embodiment of the method of manufacturing the thin filmmagnetic head according to the invention will be explained withreference to FIGS. 31–42. In these drawings, a represents a crosssectional view cut along a plane perpendicular to the air bearingsurface and b shows a cross sectional view of the pole portion cut alonga plane parallel with the air bearing surface. Also in this embodiment,a composite type thin film magnetic head is manufactured by forming amagnetoresistive type reading thin film magnetic head on a substrate andthen forming an inductive type thin film magnetic head on themagnetoresistive type thin film magnetic head.

As shown in FIGS. 31 a and 31 b, on a main substrate 21 made of anAlTiC, is deposited an insulating layer 72 made of an alumina having athickness of about 3–5 μm. In the present specification, an assembly ofthese main substrate 71 and insulating layer 72 is called substrate orwafer 73. Moreover, in the specification, the insulating layer means afilm having at least an electrically insulating property, and may or maynot have a non-magnetic property. Generally used material such asalumina has both the electrically insulating and non-magneticproperties, an insulating layer sometimes means a non-magnetic layer.

Furthermore, in a practical manufacturing, after forming a number ofthin film magnetic heads on a wafer in a matrix form, the wafer isdivided into a plurality of bars, a end surface of a bar is polished toform air bearing surfaces, and finally the bar is divided intorespective thin film magnetic heads. Therefore, during the formation onthe wafer, the end surface of the thin film magnetic head does notappear, but for the sake of explanation, this end surface is shown.

Next, on the insulating layer 72 of the substrate 73, a permalloy layerconstituting a bottom shield layer 74 for the magnetoresistive type thinfilm magnetic head is formed to have a thickness of about 3 μm. Thebottom shield layer 74 is formed in accordance with a given pattern by aplating method using a photo-resist mask.

Next, a GMR layer 76 is formed on the bottom shield layer 74 such thatthe GMR layer is embedded in a shield gap layer 75 made of alumina asillustrated in FIGS. 32 a and 32 b. A thickness of this shield gap layer75 may be 0.2 μm. On the shield gap layer 75 in which the GMR layer 76is embedded, is formed a first magnetic layer 77 made of a permalloy andhaving a thickness of 3–4 μm, said first magnetic layer constituting thetop shield for the GMR layer as well as the bottom pole of the inductivethin film magnetic head.

Next, in order to isolate the first magnetic layer 77 from a thin filmcoil to be formed later as well as to prevent a leakage of magneticflux, an alumina insulating layer 78 having a thickness of 0.3–0.7 μm isformed on the first magnetic layer 77, and then on the aluminainsulating layer, is formed an insulating layer 79 made of silicon oxideto have a thickness of 0.5–2.0 μm as shown in FIGS. 33 a and 33 b. Inthe present embodiment, this insulating layer made of silicon oxide isformed by the plasma CVD while the substrate is heat at temperature of150° C., but it may be formed by a sputtering at a room temperature.Furthermore, the insulating layer may be made of other inorganicmaterials such as alumina and silicon nitride instead of silicon oxide.

Next, the insulating layer made of silicon oxide is selectively etchedto form a band-shaped insulating layer 79, and then the aluminainsulating layer 78 is selectively etched by a reactive ion etching asshown in FIGS. 34 a and 34 b, said reactive ion etching being performedby using a freon based gas such as CF₄ and SF₆ or a chlorine based gassuch as Cl₂ and BCl₂. FIG. 35 is a plan view showing the thus formedring-shaped insulating layer 79. About a center of the ring-shapedinsulating layer 79, there is formed an opening 78 a in the insulatinglayer 78, and the first magnetic layer 77 is exposed in this opening. InFIG. 35, for the sake of clarity, a third magnetic layer constitutingthe pole chip and a thin film coil to be formed later are shown byimaginary lines.

Next, as shown in FIGS. 36 a and 36 b, a write gap layer 80 made of analumina and having a thickness of 0.1–0.3 μm is formed in accordancewith a given pattern on the exposed surface of the first magnetic layer77 and surfaces of the insulating layers 78 and 79. According to theinvention, a thickness of said ring-shaped insulating layer 79 issubstantially larger than that of the write gap layer 80. Then, a secondmagnetic layer 81 constituting the pole chip defining the track widthand made of a magnetic material having a high saturation magnetic fluxdensity is formed to have a thickness of 3–4 μm. The magnetic materialhaving a high saturation magnetic flux density may be NiFe (50%, 50%) orFeN. The second magnetic layer 81 constituting the pole chip may beformed in accordance with a given pattern by a plating method or by adry-etching after sputtering.

According to the present invention, as shown in a plan view of FIG. 35,the second magnetic layer 81 may preferably include a pole portion 81 aand a connecting portion 81 b which extends over the ring-shapedinsulating layer 79, a width of said connecting portion being graduallyincreased. This connecting portion may be formed into a triangular shapeor pentagonal shape as illustrated in FIG. 35. Since the record trackwidth is determined by a width W of the pole portion 81 a of the secondmagnetic layer 81, it is preferable to form said width narrow such as0.5–1.2 μm.

Next, as shown in FIGS. 37 a and 37 b, a part of the gap layer 80adjacent to the pole portion 81 a is selectively removed by a reactiveion etching process using a freon based gas such as CF₄ and SF₆ or achlorine based gas such as Cl₂ and BCl₂ to exposed the underlying firstmagnetic layer 77. Then, an ion beam etching process using an argon gasis conducted, while the pole portion 81 a of the second magnetic layer81 and ring-shaped insulating layer 79 as a mask such that the exposedsurface of the first magnetic layer 77 is dug down over a depth of about0.5 μm to form the trim structure. The construction of the pole portionat this processing stage is also shown in a perspective view of FIG. 38.

In the present embodiment, since the ring-shaped insulating layer 79 ismade of an inorganic insulating material, a position of the edge of theinsulating is not deviated and the insulating layer is not peeled-offduring the reactive ion etching and ion beam etching for obtaining thetrim structure. Therefore, a manufacturing yield can be improved and adurability of the magnetic head can be increased.

Next, as illustrated in FIGS. 39 a and 39 b, a first layer thin filmcoil 83 is formed within an area surrounded by the ring-shapedinsulating layer 79 such that the thin film coil is supported by aphoto-resist layer 82 in an electrically isolated manner, and then asecond layer thin film coil 85 is formed such that the tin film coil issupported by a photo-resist layer 84 in an electrically isolated manner.In the present embodiment, an air space of 2–3 μm is formed between thephoto-resist layers 82, 84 and the second magnetic layer 81.

Then, as shown in FIGS. 40 a and 40 b, a third magnetic layer 86 havinga thickness of 3–4 μm is formed in accordance with a given pattern suchthat a front end of the third magnetic layer on a side of the airbearing surface is brought into contact with the connecting portion 81 bof the second magnetic layer 81 and a rear end of the third magneticlayer remote from the air bearing surface is connected to the firstmagnetic layer 77 via the opening 78 a formed in the insulating layer 78as depicted in FIG. 41. In this manner, a contact area between thesecond and third magnetic layers 81 and 86 can be increased, and thus aleakage of magnetic flux at the pole portion can be further effectivelysuppressed. Such an advantage is particularly important when a width ofthe first layer 81 constituting the pole chip is not larger than 100 μm.

Furthermore, as illustrated in FIGS. 42 a and 42 b, an overcoat layer 87made of an alumina and having a thickness of 20–30 μm is formed on awhole surface. As stated above, in the practical manufacturing process,the wafer is cut into bars and a side face of a bar is polished to formthe air bearing surface. In the present embodiment, a position of theedge of the ring-shaped insulating layer 79 on a side of the air bearingsurface is used as the reference position and this position is notshifted during the manufacturing, and therefore it is possible to obtaineasily the throat height TH having a desired design value.

In the present embodiment, the band-shaped insulating layer 79 having alarge thickness is formed in a ring-shape and the thin film coil 83, 85is arranged within the ring. According to the invention, the band-shapedinsulating layer is not always necessary to be formed into a ring-shape,but may be formed in any other shape. For instance, the insulating layermay be formed as a frame shape as shown in FIG. 43 or may be formedrectilinearly as illustrated in FIG. 44. According to the invention, aslong as the band-shaped insulating layer 79 has an air bearing surfaceside edge which can define the throat height zero position and has athickness larger than that of the write gap layer, it may be formed intoany shape as shown in FIGS. 30 a–30 i.

Moreover, in the present embodiment, the connecting portion 81 b of thesecond magnetic layer 81 and the third magnetic layers 86 are joined toeach other at the surface, side walls and end surface of the connectingportion. However, according to the invention, the third magnetic layer86 may be brought into contact with the surface and side walls of theconnecting portion 81 b of the second magnetic layer 81 as illustratedin FIG. 44.

The present invention is not limited to the embodiments explained above,but many alternations and modifications may be conceived by thoseskilled in the art. For instance, in the above mentioned embodiments,the connecting portion of the second magnetic layer and the frontportion of the third magnetic layer lying over the connecting portionare formed to be gradually widened. The second magnetic layer 91 may beformed such that a pole portion 91 a is connected to a connectingportion 91 b at right angles as shown in FIG. 45. In this case, awidening angle of the connecting portion 91 a of the second magneticlayer 91 may be considered to be 180°. Also in this case, the front endportion of the third magnetic layer 96 extending over the connectingportion 91 b of the second magnetic layer 91 may be formed to have aconstant width in accordance with a shape of the underlying connectingportion. Even if the widening angle is set to 180°, it has beenexperimentally confirmed that the improved over write property can beobtained and an increase in the effective track width can be suppressed.

Further, in the above embodiments, the reading magnetoresistive typethin film magnetic head is provided on the substrate and the writinginductive type thin film magnetic head is stacked on the readingmagnetic head, but according to the invention this stacking order may bereversed. In the above embodiments, the magnetoresistive element isformed by a GMR element, but it may be formed by an AMR element.Moreover, according to the invention, the reading thin film magnetichead is not limited to the magnetoresistive element, but may be formedby any other thin film magnetic head. It should be further noted thatthe reading thin film magnetic head is not always necessary, but onlythe inductive type thin film magnetic head may be provided.

According to the invention, the second magnetic layer constituting thepole chip may be advantageously made of any kind of a magnetic materialhaving a high saturation magnetic flux density such as a Fe—Cr—Zr basedamorphous alloy and a Fe—C based amorphous alloy in addition to theabove mentioned permalloy (Ni: 50%, Fe: 50%) and iron nitride (FeN). Itshould be noted that plural layers of two or more than two kinds ofthese materials may be stacked.

The first and third magnetic layers may be advantageously made of knownmagnetic materials having a high saturation magnetic flux density inaddition to the above mentioned permalloy (Ni: 80%, Fe: 20%).

The write gap layer may be made of an oxide such as Al₂O₃ and SiO₂, or anitride such as AlN, BN and SiN, or an electrically conductive butmagnetically non-conductive material such as Au, Cu and NiP.

In the embodiments shown in the drawings, the insulating layer havingthe edge on a side of the air bearing surface side gives the referenceposition for the air bearing surface is made of a photo-resist, butaccording to the invention, this insulating layer may be made ofalumina, silicon or silicon nitride.

In the first embodiment, the insulating layer 28 is made of aphoto-resist and in the second embodiment, the insulating layer 78 ismade of a silicon oxide, but they may be made of other inorganicinsulating material. However, these insulating layers are preferablymade of an inorganic insulating material from a view point that theselayers serve as a mask in the etching process for forming the trimstructure.

According to the present invention, the band-shaped insulating layer isprovided on the first magnetic layer such that the edge of theinsulating layer on a side of the air bearing surface defines thereference position for the air bearing surface, and this insulatinglayer is covered with the write gap layer made of alumina. Therefore,the insulating layer is not melt by the heating treatment during theformation of the thin film coil and a position of the edge is notshifted, and thus the throat height TH, MR height MRH and apex angle θcan be formed accurately in accordance with desired design values.

Therefore, according to the invention, there is always existent adesired relationship between the throat height TH and the MR height MRH,and thus the writing head and reading head can be remained always in anoptimum condition. As the result of this, it is possible to provide acomposite type thin film magnetic head having a superior performance.

Moreover, according to the invention, the second magnetic layer (polechip) and the third magnetic layer top pole) are joined to each othernot only at the pole portion, but also at the rear portion having alarger surface area, and the magnetic flux generated by the coil is notsaturated and a leakage of the magnetic flux at the connecting portioncan be suppressed, and thus data can be recorded efficiently on a verynarrow track. In this manner, it is possible to obtain a satisfactorywriting performance. That is to say, the third magnetic layer may bebrought into contact with the surface, or the surface and side walls, orthe surface, side walls and end surface of the connecting portion of thesecond magnetic layer, and a very large contact area can be obtained.

Moreover, by widening the rear portion of the second magnetic layer, acontact area between the top pole and the pole chip can be increased,and thus a leakage of the magnetic flux at this portion can beeffectively prevented.

By widening the third magnetic layer covering the second magnetic layer,even if an error is introduced in an alignment of these layers, acontact area is not changed and a leakage of magnetic flux can be stillavoided.

Furthermore, according to the invention, the front end of the thirdmagnetic layer is retarded from the air bearing surface and a contactportion between the second and third magnetic layers is not exposed onthe air bearing surface, and therefore even if a relative position ofthe top pole with respect to the pole chip deviates viewed from the airbearing surface, the writing operation through the top pole can beavoided and an increase in the effective track width can be prevented.

Moreover, according to the invention, since the apex height can bereduced as compared with the known thin film magnetic head, a trackwidth of the recording head can be effectively reduced, or if the apexangle is set to be substantially equal to that of the known head, thenumber of coil windings can be increased accordingly and the recordingperformance can be improved.

In the embodiment of the thin film magnetic head according to theinvention, in which the band-shaped insulating layer is formed into aring-shape and the thin film coil is formed within the ring, a height ofthe thin film coil consisting of two or three layers can be reduced by adistance substantially equal to a thickness of the insulating layer, andthus the apex angle can be decreased and the number of coil windings canbe increased. In this manner, an efficiency of the thin film coil can beimproved.

Further, as shown in the second embodiment, when the band-shapedinsulating layer having a large thickness is made of an inorganicmaterial, the edge of the inorganic insulating layer is hardly shiftedduring the etching process for forming the trim structure, and thus aportion of the insulating layer situating under the second magneticlayer constituting the pole chip is neither damaged nor peeled-off and aposition of the insulating layer is not shifted. Therefore, adegradation of the performance of the thin film magnetic head can besuppressed. Further, since the insulating layer is not peeled-off, nooil and polishing liquid could not be retained between the insulatinglayer and the first magnetic layer, a manufacturing yield can beincreased and a durability of the thin film magnetic head can beprolonged.

1. A thin film magnetic head comprising: a substrate having a majorsurface; a first magnetic layer formed on or above the major surface ofthe substrate and having a pole portion; a second magnetic layer havinga pole portion which is opposed to said pole portion of the firstmagnetic layer via a write gap layer and constitutes an air bearingsurface together with said pole portion of the first magnetic layer, anda rear portion; a third magnetic layer having a front portion connectedto the rear portion of said second magnetic layer, a front end surfaceof said front portion being positioned near the air bearing surface butdisplaced rearwardly in a direction of the rear portion of the secondmagnetic layer, and a rear portion of the third magnetic layer beingmagnetically coupled with the first magnetic layer at a position remotefrom the air bearing surface; and first and second layers of thin filmcoil having portions formed between said first and second magneticlayers; wherein said first layer of thin film coil is embedded within afirst insulating layer; a second insulating layer is provided on thefirst insulating layer such that a surface of the second insulatinglayer opposite to the first insulating layer is coplanar with a surfaceof the rear portion of the second magnetic layer opposite to the writegap layer; and the second layer of thin film coil is formed on thecoplanar surface of the second insulating layer and is embedded within athird insulating layer.
 2. The thin film magnetic head according toclaim 1, wherein said first insulating layer and the third insulatinglayer are made of photo-resist and said second insulating layer is madeof alumina.
 3. The thin film magnetic head according to claim 1, whereina surface of a front portion of the second magnetic layer opposite tothe write gap layer is closer to the write gap layer with respect to thecoplanar surface of the second insulating layer.
 4. The thin filmmagnetic head according to claim 1, wherein a surface of a front portionof the second magnetic layer opposite to the write gap layer extendsalong the coplanar surface of the second insulating layer.